1. Spine Surgery Division, Hospital for Special Surgery, New York City, NY
2. Department of Neurosurgery, Thomas Jefferson University School of Medicine, Philadelphia, PA
3. Department of Orthopedics, Emory University School of Medicine, Atlanta, GA
4. Department of Neurosurgery, NewYork-Presbyterian Hospital/Weill Cornell Medical Center, New York City, NY
5. Rothman Orthopaedic Institute, Thomas Jefferson University School of Medicine, Philadelphia, PA